pythongh-126105: Fix crash in ast module, when ._fields is deleted

sobolevn · Oct 29, 2024 · 4186e14 · 4186e14
1 parent 9b14083
commit 4186e14
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Showing 3 changed files with 28 additions and 8 deletions.
diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
@@ -84,6 +84,23 @@ def test_AST_objects(self):
             # "ast.AST constructor takes 0 positional arguments"
             ast.AST(2)
 
+    def test_AST_fields_NULL_check(self):
+        # See: https://github.com/python/cpython/issues/126105
+        old_value = ast.AST._fields
+
+        def cleanup():
+            ast.AST._fields = old_value
+        self.addCleanup(cleanup)
+
+        del ast.AST._fields
+
+        msg = 'AST has no fields'
+        # Both examples used to crash:
+        with self.assertRaisesRegex(TypeError, msg):
+            ast.AST(arg1=123)
+        with self.assertRaisesRegex(TypeError, msg):
+            ast.AST()
+
     def test_AST_garbage_collection(self):
         class X:
             pass

diff --git a/Misc/NEWS.d/next/Library/2024-10-29-11-45-44.gh-issue-126105.cOL-R6.rst b/Misc/NEWS.d/next/Library/2024-10-29-11-45-44.gh-issue-126105.cOL-R6.rst
@@ -0,0 +1 @@
+Fix a crash in :mod:`ast` when ``_fields`` attribute is deleted.
diff --git a/Python/Python-ast.c b/Python/Python-ast.c